This invention relates to a vertical die casting device which consists of a sleeve connecting the pouring gate and the cavity gate and of a plunger tip inserted in the upper portion of the sleeve for injecting molten metal under pressure and a counter tip inserted in the lower portion of the sleeve for guiding the molten metal into the cavity gate. More particularly this invention relates to a vertical die casting device in which the counter tip is made to retract at the same time and at the same speed as the plunger tip moves down so that the molten metal can be poured, without being pressurized, into the cavity.
In the conventional vertical die casting devices, as shown in FIG. 1, a plunger tip 4 and a counter tip 5 are disposed opposite to each other in the sleeve 3 that connects the pouring gate 1 and the cavity gate 2. When the counter tip 5 is at a position that closes the cavity gate 2, the molten metal 6 is poured from the gate 1 into the sleeve 3 and then the plunger tip 4 is forced down by a proper pressure application mechanism to apply pressure to the molten metal so as to push down the counter tip 5 via the pressurized molten metal and cause the molten metal to flow into the cavity through the cavity gate 2.
This construction, however, has disadvantages: that is, since the molten metal 6 in the sleeve 3 is pressurized between the plunger tip 4 and the counter tip 5, the resulting increase in adhesion between the molten metal 6 and the sleeve 3 or the tips 4, 5 allows more heat to be transferred to the sleeve and tips, resulting in reduction in the temperature of molten metal. This can prevent a smooth flowing of the molten metal into the vacity or reduce the life of the sleeve 3 and tips 4, 5.